Western Capercaillie

Fascinating facts about the Western Capercaillie

• A male western capercaillie can reach up to 100 cm in length and weigh up to 6.7 kg, while the biggest captive bird weighed 7.2 kg.
• When a cock takes off it produces a sudden thundering noise that deters predators, then it glides in short bursts and its feathers produce a whistling sound.
• The global population is estimated at 1.5–2 million individuals.
• In Scotland the wild population fell from about 10,000 pairs in the 1960s to just 532 birds by 2025, a drop of more than 95 %. The collapse highlights how fences for deer and ski-lift cables can become lethal traps for ground-dwelling birds.
• The bird’s diet hinges on bilberry shrubs and a patchy mosaic of old spruce and pine with dense undergrowth; without that mix, chicks lose both food and insect protein. This reliance shows that preserving complex, multi-layered forests is essential for their survival, not just planting single-species trees.

About the Western Capercaillie

The western capercaillie (Tetrao urogallus) is the heavyweight of the grouse tribe, with males stretching 74–85 cm in length, a wingspan of 90–125 cm and weighing up to 4.1 kg, while the largest wild cocks can reach 100 cm and 6.7 kg. Their plumage is a dramatic tapestry: dark grey-brown body feathers, metallic-green breast, and a belly that ranges from black to almost pure white in eastern races. A bright red spot of bare skin crowns each eye, and a white wing-bow spot marks both sexes. Females are half the size, 54–64 cm long, weighing 1.5–2.5 kg, with brown, black-silver barred upperparts and a buff-yellow underside. These birds are ground-bound forest specialists, thriving in mature conifer stands with a light canopy and a dense understory of Vaccinium shrubs such as bilberry and blaeberry. Their diet is heavily plant-based, supplemented by insects for chick growth, and they rely on old trees with horizontal branches for roosting. A surprising trait is their “courting track” – a snowshoe-like imprint left by feathered legs that reveals the male’s elaborate lek display, a ritual that can fill the winter air with a thunderous take-off and a whistling wing sound as the bird launches from the forest floor.

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